If you disable the CPU's onboard video you will get app crashes and BSOD's regardless of what RAM timings & voltage you use. This apparently effects multiple brands of Z77 & Z87 motherboards but most complaints seem to be with Gigabyte boards.

Make sure to enable the CPU's onboard video if you're getting crashes with four 8gb sticks. Its OK if you have a discrete graphics card, just plug the monitor you use for gaming into the GPU and games will use it instead of the onboard video.

I had this problem on a Gigabyte Z87X-UD4H mobo with 4x8gb Mushkin 997110 RAM. Increasing RAM voltage and decreasing timings didn't help at all. After enabling on-board video my system is now 100% stable using the RAM's XMP profile.